This gave Manfred a strategically vital beachhead in the Balkans, controlling the western terminus of the great Via Egnatia, the main overland route to Constantinople.

Taking advantage of Charles's entanglement in the conflict between Guelphs and Ghibellines in Italy, in spring 1274 Michael launched an attack against Angevin holdings in Albania.

[5] In August 1279, in preparation for resuming his offensive against Michael along the Via Egnatia, Charles appointed as his vicar-general in Albania the Burgundian Hugo de Sully.

[6] In August/September 1280, with an army of 2,000 knights and 6,000 infantry, Sully began his attack by storming the fortress of Kanina and then advancing to central Albania and laying siege to Bellegrada.

If it were taken, the Empire would lie open to an invasion, which, if joined by the Latin states of Greece and the Greek rulers of Epirus and Thessaly, might result in the fall of Constantinople to Charles.

[7] Responding to the pleas for reinforcements of the governor of Bellegrada, Michael VIII ordered special prayers for the salvation of the Empire, and assembled an army headed by some of his best generals.

He ordered his governors in Albania to direct all their resources towards the siege, and displayed his close interest by a series of letters to Sully, instructing him to take the city by assault if necessary.

The many prisoners, including Sully, were taken to Constantinople, where they were publicly paraded in a triumph celebrated by the exultant emperor, who further ordered frescoes depicting scenes from the campaign painted in his palace.

The defeat ended Charles's designs of an overland assault on Byzantium, but the Angevin ruler now redoubled his efforts, aiming to launch a seaborne invasion of the Empire with Venetian aid.

The Papacy also, after the election of the pro-Angevin Martin IV, finally sanctioned his plans, excommunicating Michael Palaiologos and ending the Union of the Churches.